How do I achieve an image lit by candle light?
If you are using cycles. You don't need much. If you are using cycles you can use an emitter shader as the flame, not much else, as the candle will light the scene.

Then read the following link: 

Make the flame of a candle more yellow

There are options there to use the compositor, to create materials that are brighter for the scene and less bright for the camera, as well as using color management to create a more realistic